Arrangement for improving operation of hydraulic turbine



Nov.

24, 1959 P. D, HESS 2,914,301

ARRANGEMENT FOR IMPROVING OPERATION OF HYDRAULIC TURBINE Filed July 22.1957 Q /Maori fem Vt 94/9/90 United States Patent ARRANGEMENT FORIMPROVING OPERATION OF HYDRAULIC TURBINE Paul D. Hess, Brookfield, Wis.,assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application July 22, 1957, Serial No. 673,415

7 Claims. (Cl. 253-117) This invention relates to hydraulic turbines andmore particularly to an arrangement for admitting air below the runnerto improve the operation of the turbine.

A hydraulic turbine is designed so its efficiency is best atfull load.At part loads there are occasions when thewater stream causes voids tobe formed below the runner. This results in noise and rough operation.

One way of controlling the noise and rough operation is to admit airinto the area where the voids are formed. Air can be introduced into thewater stream through ports provided in a hollow cap attached to the endof the runuer. This is well known. See, for example, U.S. Patent2,079,258 to Kerr.

. Normally, vacuum created by the water stream moving by the hollow capdraws air through ports in the cap into the area subject to the voids.The source of air can be the atmosphere. This is also well known.

Therekis a disadvantage in relaying on vacuum per se to draw the airthrough the ports in the cap. The vacuum may be weak and cannot draw inenough air to beefiective. Also under conditions of high tail water,there may be a slight back pressure in the area around the cap of therunner suflicient to counteract atmospheric pressure and the effect ofthe water stream moving by the cap of the runner tending to draw air outthrough the ports. A slight back pressure will not however eliminatevoids, it merely makes more difficult the problem of getting air to thelocation of a void and a pressure greater than atmospheric will berequired to move the air from the ports to such locations.

Essentially, my invention involves connecting a series of vanes to apart of the turbine that rotates. The rotating part will rotate thevanes. The vanes will act as a compressor, forcing air through theinterior of the hollow cap at the end of the runner and out ports in theside of said cap.

My invention also involves providing openings in said vanes. Fluid canflow through the openings in the vanes to unblocked ports if a port, orports, becomes blocked. This way fluid cannot be trapped between vanes.Also, the vanes continue to function, in that they can supply fluid tounblocked ports.

It is an object of my invention to provide an improved arrangement thatintroduces a larger amount of air into the water stream than haspreviously been possible, and which also introduces air into the waterstream under conditions when this could not be done previously.

It is another object of my invention to provide an improved capcontaining vanes, whereby the vanes will continue to function if some ofthe ports in the cap become blocked.

It is another object of my invention to provide an improved capcontaining vanes, that can be easily attached to and disconnected fromthe runner to facilitate maintenance or substitution of caps.

Other objects and advantages will appear from the ice followingdescription considered in conjunction with the attached drawing, inwhich:

Fig. 1 is a sectional view of a hydraulic turbine showing the hollow capconnected to the runner; and

Fig. 2 is a plan view of the hollow cap taken in the direction of arrowsIIII of Fig. 1.

Referring to Fig. 1 there is disclosed a portion of a hydraulic turbine2 in this instance, a Francis turbine. Broadly,turbine 2 comprises: headcover 4 that is stationary and serves as a support for rotating element6 which carries blades 8, a spiral casing 10 (only a portion beingshown) through which the water stream flows to blades 8, and a series ofwicket gates 12 that control the flow of the water stream from spiralcasing 10 to blades 8. After passing through the blades the water streamexits through a draft tube 14.

Rotating element 6 comprises: shaft 16, runner 18, and cap 20. Shaft 16is connected at one end to a generator (not shown). The other end ofshaft 16 is provided with coupling flange 22. Coupling flange 22 isconnected by bolts 24 to runner 18 which carries blades 8. Cap 20 isconnected to the under surface of runner 18. Cap 20 guides the water asits leaves blades 8.

Cap 20 is hollow and cone shaped. The cap is made up of cone portion 26,cylindrical portion 28 connected to the large diameter end of the coneportion, and flange portion 30 supported by cylindrical portion 28.Flange portion 30 is normal to, and faces the axis of cone portion 26.Flange portion 30 is removably secured by bolts 32 to runner 18.

Although other connecting means can be used, the cone portion,cylindrical portion and flange portion are secured together by welding.

The bottom of cone portion 26 is closed by cover plate 34. Cover plate34 is removably connected by bolts 36 to plate 38 fastened to theinterior of the small diameter end of cone portion 26. Plate 38 has anopening 48 in its center for entrance to the interior of the cap, andfor access to bolts 32 that connect flange portion 30 to runner 18.

Attachment as well as maintenance of cap 20 is easy. All that isnecessary is that cover plate 34 be removed for access to the interiorof cap 20.

Connected to the inside surface of the cap are a plurality of vanes 42.Vanes 42 have a bottom portion 44, and a top portion 46 positionedobliquely above and out wardly of said bottom portion. Bottom portion 44abuts plate 38, and top portion 46 abuts flange portion 30.

Any connecting means can be employed to connect vanes 42 to cap 20. Inthe embodiment disclosed, the edge of vanes 42 are welded to the cap.

As can be seen in Fig. 2, vanes 42 extend toward the axis of therotating element and form a fan member. Ports 48 (Fig. l) are located incone portion 26 intermediate top and bottom portions 44, 46 of saidvanes. There is a port provided between adjacent vanes.

Although only a single port (Fig. 2) is illustratedbetween adjacentvanes, obviously additional ports can be provided. Also, although thevanes are illustrated as straight (Fig. 2), the vanes can be curved toprovide a larger vane surface. It is further noted that vanes 42 havethe additional function of strengthening the cap, since they will alsoact as reinforcing members.

Occasionally a port, or ports, may become clogged by foreign matter. Inthat event, vanes 42 directing fluid to those ports would becomeuseless.

In addition, when rotating element 6 is not rotating, water flows blackthrough ports 48 in cap 20 flooding head cover 4. Normally, whenrotating element 6 starts rotating, the water flows back out ports 48.However, if some ports 48 are blocked, water can be trapped be- 3 tweentwo adjacent vanes (Fig. 2) and slightly unbalance runner 18.

To prevent water from being trapped between the vanes, or the vanes fromnot functioning, openings 50: are

provided in the edge of each vane connected to the inside surface ofconeportion 26. Openings 50 permit fluid, which can be air or water, to flowfrom ports 48 which may be clogged to other ports 48 that are open. Inthis way, the vanes continue to operate if some ports are blocked.

Ports 48 in cap 20 are connected by passage means to a source of air(not shown) outside the runner. The passage means comprises: theinterior of cap 20 which contains vanes 42, axial passage 52 in shaft16, radial passages 54, and passages 56 in head cover 4. It is notedthat vanes 42 are in the passage means.

Air from the source passes through passages. 56 in the head cover 4,radial passages 54, axial passage 52, the interior of the cap 20, andout ports 48.

Although passages 54 are illustrated as extending radially, they can bedispensed with and axial passage 52 extended the length of shaft 16 anddirectly connected to a source of air.

In summary:

My invention provides a new improved arrangement that utilizes vanesthat are turned by the rotating element to force air into the waterstream below the runner.

My invention provides a simple arrangement wherein vanes on the insideof the cap are provided with openings so they continue to function evenwhen ports between them become blocked.

And finally, my invention provides a simple cap containing vanes, whosecover plate can be easily removed to provide access to the vanes, portsor bolts so the cap can be attached or removed from the runner tofacilitate maintenance or substitution of caps.

Although but a single embodiment of the present invention has beenillustrated and described, it will be apparent to one skilled in the artthat various changes and modifications may be made therein withoutdeparting from the spirit of the invention or from the scope of theappended claims.

What is claimed is:

1. A hydraulic turbine comprising; a rotating elemen rotated by a waterstream, said rotating element including a shaft and a runner connectedto said shaft, a hollow cap connected to said runner, a plurality ofports in the surface of said hollow cap, passage means conmeeting saidports to a source of air external of said turbine, a plurality of spacedvanes in said passage means, means connecting said spaced vanes to saidrotating element, said vanes rotating in response to rotation of saidrotating element, said vanes on rotating drawing air from said sourcethrough said passage means and forcing said air out said ports in saidcap below said runner.

2. A hydraulic turbine comprising; a rotating element rotated by a waterstream, said rotating element including a shaft and a runner connectedto said shaft, a hollow cap connected to said runner, a plurality ofspaced vanes, means connecting an edge of each of said vanes to theinside surface of said hollow cap, said vanes extending toward the axisof said runner and forming a fan member, said vanes having top andbottom portions, said top portions positioned obliquely above andoutwardly of said bottom portions, a plurality of ports in the surfaceof said cap, passage means connecting said ports in said hollow cap witha source of air external of said turbine, said ports located in said capintermediate the top and bottom portions of said vanes, said vanes whenrotating drawing air from said source into said cap, and moving said airradially so it discharges out said ports.

3. A device as set forth in claim 2 wherein each of said vanes connectedto the inside surface of said hollow cap is provided with an opening, sofluid can pass from a blocked port through said openings to an unblockedport.

4. A device as set forth in claim 3 wherein each of said openings insaid vanes is in the edge of said vanes that is connected to said cap.

5. In a hydraulic turbine, an improved cap for the runner of a hydraulicturbine, said cap comprising: a

cone shaped portion that guides the fluid stream, a plu rality of portsin said cone shaped portion, a cylindrical portion connected to thelarge diameter portion of said cone portion, a flange on said coneportion normal to and facing the axis of said cone portion, meansconnecting said flange to said cylindrical portion, means removably'connecting said flange to said runner, a plate having an opening, means.connecting said plate to the small diameter end of said cone portion, acover plate, means re movably connecting said cover plate to said plate,said cover plate closing said opening in said plate, a plurality ofspaced vanes, and means connecting said spaced vanes to the innersurface of said cap locating said plurality of vanes in spacedintermediate lateral relation with said plurality of ports and inintermediate relation with re spect to said cover plate and said flange.

6. A device as set forth in claim 5 wherein each of said vanes connectedto the inside surface of said hollow cap is provided with an opening, sofluid can pass from a blocked port through said openings. to anunblocked port.

7. A device as set forth in claim 6 wherein each of said openings insaid vanes is in the edge of said vanes that is connected to said cap.

References Cited in the file of this patent UNITED STATES PATENTS GreatBritain June 20, '1956'

